1. Field of the Invention
The present invention relates to a gas laser apparatus using a gaseous laser medium. The present invention also relates to a method and device for monitoring a maintenance state of a blower adapted to be provided in a gas laser apparatus.
2. Description of the Related Art
A gas laser apparatuses using a gaseous laser medium is widely used in the field of processing, medical care, measurement and so on. A laser oscillating section of the gas laser apparatus generally includes an excitation section for exciting, by electrical discharge, light, heat, chemical reaction and the like, a flowable gas acting as a laser medium (referred to as a medium gas in this application); a light resonance section, having a pair of mirrors, for amplifying light energy of the medium gas excited by the excitation section and generating a laser beam; and a blower for forcibly circulating the medium gas in a medium circuit including the excitation section and the light resonance section.
In order to improve the characteristics or quality of the generated laser beam under given dimensional limitations of the gas laser apparatus, it is required that the blower provided in the gas laser apparatus for circulating the medium gas can achieve large capacity and high-speed rotation. Moreover, the blower of this type is exposed to high temperature when the laser beam is generated, and therefore, a lubricant or lubricating oil, supplied to a bearing section of an impeller, is likely to be degraded in quality. Thus, the lubricant or lubricating oil, contained in the blower, has to be periodically changed. However, when the maintenance/inspection time of the lubricant is managed manually by an operator, human errors such as oversight of the inspection time may occur. In order to solve this problem, as described in, for example, Japanese Patent No. 2622424 (JP-2622424-B2), a gas laser apparatus that can automatically manage maintenance and inspection time has been proposed.
The gas laser apparatus described in JP-2622424-B 2 includes a maintenance-time monitoring device for automatically managing maintenance and inspection time with regard to various items to be maintained, such as lubricant change in a blower, by monitoring an operating time of an object to be maintained. The maintenance-time monitoring device includes time-measuring means for measuring the operating time of the object to be maintained (e.g., a blower); time-limit alarm means for outputting an alarm signal at an instant when a measured operating time reaches a predetermined time; maintenance-time display controlling means for controlling a display unit so as to display the arrival of a maintenance time (e.g., a lubricant changing time) in response to the output of the alarm signal; and resetting means for resetting a time measurement performed by the time-measuring means and canceling a display instruction issued by the maintenance-time display controlling means, according to a signal indicating that the maintenance operation (e.g., a lubricant change) has been performed. In this connection, a signal issued by a limit switch, incorporated into a cap for closing a lubricant inlet of the blower, upon detecting the detachment or attachment of the cap, is given to the resetting means, which is a signal indicating that, for example, a lubricant or lubricating oil in a blower has been changed.
In the maintenance-time monitoring device of the gas laser apparatus, described in JP-2622424-B2, the cap detachment/attachment detecting signal issued from the limit switch incorporated into the cap of the lubricant inlet of the blower is adopted as the signal indicating that the lubricant in the blower has been changed. However, the lubricant in the blower is typically changed while the gas laser apparatus is de-energized in view of safety. In this connection, the maintenance-time monitoring device is incorporated into a control section for controlling the exciting and resonating operation of the medium gas in the gas laser apparatus, and therefore, in a state where the gas laser apparatus is de-energized, it is difficult to determine by a predetermined signal, whether the lubricant in the blower has been changed or not. In this regard, JP-2622424-B2 teaches a technique in which a signal indicating that the lubricant in the blower has been changed is manually input by, for example, a keyboard. In this technique, after the lubricant change is completed and the gas laser apparatus is energized, an operator uses the keyboard to input a lubricant-change completion signal, and thereby the resetting means of the maintenance-time monitoring device resets the time measurement performed by the time-measuring means and cancels the display instructions issued by the maintenance-time display controlling means.
When the technique for manually inputting the lubricant-change completion signal is adopted, burden on the operator may be increased, erroneous instructions by the operator may happen, and as a result, an unintended reset operation (i.e., initialization of management data) may take place. Further, when the lubricant in the blower is changed, since an internal space of the medium circuit of the gas laser apparatus is exposed to environmental air, impurities or foreign matter, other than the medium gas, may enter the excitation section or the light resonance section, and as a result, the hermetical feature of the medium circuit may be impaired. Therefore, after the lubricant is changed, an operation for checking the leakage of the medium gas in the medium circuit (so-called, a leak-checking) and/or removing foreign matter that have entered the medium circuit (so-called, an aging) are typically performed. In this regard, if the above described conventional maintenance-time monitoring device is used, the operator manually inputs, for convenience, instructions for the gas laser apparatus to perform leak-checking or aging, after the operator has manually input the lubricant-change completion signal. As a result, burden on the operator may be significantly increased, and the frequency of erroneous instructions by the operator may be increased.